1. Technical Field
The present invention relates to an ink composition, an ink set, and a black ink set.
2. Related Art
As a liquid ejecting apparatus for ejecting liquid onto a target, an ink jet printer for ejecting ink onto a recording medium (hereinafter, simply referred to as a printer) is known. In this printer, in order to reduce the ejection failure of ink, cleaning for discharging the ink or the like thickened from an injection nozzle for ejecting ink has been appropriately carried out.
In this cleaning, a nozzle formation surface provided with nozzles is sealed with a suction cap, and then a space (in the suction cap) hermetically closed with the nozzle formation surface and the suction cap is vacuumed up by a suction pump. That is, in the cleaning, a space having negative pressure is formed in the discharge direction of ink, and the thickened ink or like is discharged from a nozzle by using the negative pressure.
In such cleaning, generally, the ink discharged from the nozzle is sucked by the suction pump through the suction cap, and is then discharged to an ink recovery unit as a liquid recovery unit. In such an ink recovery unit, an ink absorber for absorbing ink is contained. This ink absorber absorbs the discharged ink, thereby recovering the ink discharged from the suction pump.
As an example of the technology focusing on an ink recovery unit, JP-A-2006-21451 is known. JP-A-2006-21451, for the purpose of providing a liquid absorber for eliminating the bubbles contained in the liquid discharged from an outlet of a suction pump to a liquid recovery unit and smoothly absorbing and recovering the discharged liquid, discloses a liquid absorber for absorbing the liquid discharged from an outlet of a suction means depressurizing the space by suctioning liquid and gas, in which the liquid absorber includes a defoaming agent for eliminating the bubbles contained in the liquid discharged from the outlet.
However, in the technique described in JPA-2006-21451, there is a problem that a mechanism for supplying a defoaming agent to the liquid absorber of the liquid recovery unit in a recording apparatus is further required.
Further, the ink sucked through the nozzle contains the bubbles generated therein by the suction (negative pressure). Through the suction cap, fine bubbles are discharged together with the thickened ink. Since it is difficult for these bubbles to be absorbed by the ink absorber in the suction cap, an ink composition accumulates in the suction cap, and eventually the ink composition overflows from the suction cap. When the ink composition overflows from the suction cap, there is a concern that the nozzle formation surface is contaminated during the cleaning, and thus cleaning-induced ejection failure occurs.